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nited States Patent PROCESS FOR THE MANUFACTURE OF A PQLYENE ALDEHYDE 1 ciaims priority, applicat ion switz erland July 10, 1953 This invention relates to a process forthepreparation of hitherto unknown polyene dialdehydes, which comprises acetalising an unsaturated 217 -dimethyl-octane dial having three conjugated multiple bonds between the aldehyde groups, condensing the obtained diacetal with 2 moles of a vinyl ether in the presence of an acidic condensing agent, and treating the obtained condensation product with acid to cause hydrolysis and elimination of alcohol in order to term the corresponding unsaturated 4z9-dimethyl-dodecane dial.

The obtained polyene dialdehydes, i. e. 4:9-dimethyldodecatetraen-(2z4: 8: 10)-yn-,(6)-dial-( 1: l2) and 4:9-dimethyl-dodecapentaen-(Z 4:6 8: l)-dial-( 1 :2), hereinafter' referred to as C14 dialdehydes, are valuable intermediates for the synthesis of polyene dyestuffs. Thus, the Reformatsky reaction results in the formation of dehydrocrocetin and crocetin when using 2 moles of abromo-propionic acid ester withsubsequent elimination of water and saponification. By acetalising the C14 dialdehydes, condensing the formed acetals with 2 moles ofpropenyl ether and treating the condensation products with acid, dehydrocrocetindialdehyde and crocetindialdehyde are formed. In the Reformatsky reaction of pose. The obtained acetals of the C10 dialdehydes are colorless oils having two absorption maxima in the ultraviolet spectrum at 273 m and 288 m No particular purification, for example by distillation, is necessary prior .to the further treatment of the said acetals.

' in the second step theabove-described C10 diacetal is condensed with ,a vinyl ether in thegpresence of an acidic condensing agent tolform the C14; 'di-etheracetal.

Condensing agents which cambeused rforrthis-conclensation are BFg-etherate, ZnClayIiClr, A1Clii, FCl3, SnCl4 etc. It is convenient to use. the.vinyl ether of the same alcohol with which the C10 dialdehyde has been acetalised, for example methyl vinyl ether, ethyl vinyl ether, or nbutyl vinyl ether. The cond ensation is carried out at as ,low a' reaction temperatureas possible. In this manner 1 undesired side reactionssuch as polymerisation and condehydrocrocetin dialdehydeand crocetin dialdehyde, re-

spectively, with bromo-acetic ester .with subsequent elimination of water, all-trans dehydrobixin ester and alltrans bixin ester, respectively, are formed. When acet- 1 alising dehydrocrocetin dialdehyde and crocetin dialdehyde, respectively, condensing the so, obtained acetal with 2 moles of vinyl ether andtreatingthe condensation products with acid, dehydrobixin dialdehyde and bixin dialdehyde, respectively, are formed. In the Grignard reaction of dehydrobixin dialdehyde and bixin dialdehyde, respectively {with two moles of 2 methyl-6-bromohepten-(2) with subsequent elimination of water, dehydrolycopene and lycopene, respectively, are formed.

' In' the preferred embodiment of the presentinvention,

2:7-diniethyl-octadien (2i6 )-yn (4)-dial-(1f8) [C10 dialdehyde] is acetalised, the obtained 2:,7-dirnethy1-octadien-(2b6) yn (4)-diacetal-(1 :8) [C11 diacetall is condensed with a vinyl ether in the presence of an acidic condensing agent, and the so obtained 4:9-dimethyl-dodecadien-(4: 8)-yn-(6)-diether-(3 10)-'diacetal-( 1 12) [C14 diether acetal] is treated with acid to cause hydrolysis and elimination of alcohol from the positions 2:3 and 10:11 in order to form 4:9-dimethyldodecatetraen- (2:4:8:10)-yn-(6) dial(l:l2) [C14 dialdehyde].

Thefirst step of the process according tothe present invention consists in a'cetalising the C10 dialdehyde. This is carried out in a manner known per se. Thus, the acetalisation is carried out, for ,example, by means of an drtho-ester in the presence of an aeidic condensing agent such asp-toluene sulfonic acid, phosphoric acid BFa-etherate, ZnClz, NHCl, N I- I4NO3,'and the like. The ortho-esters of lower aliphatic acids with lower aliphatic alcohols, preferably th e methyl, ethyl, or n-butyl ortho- M formates, are particularly convenient for th e saidpun 60 tron.

in theultra-violet spectrum'at 273 to 274 111 and 288 to 290 m 1. No particular purification, for example by distillation, is, necessary prior. to the further treatment of these products.

The third step consists;in ihydrolysing the C14 dietheracetals in an acidic me dium by a method known per S6, wherebythe C14dialdehyde is formed by simultaneous elimination of, alcohol from the "positions 2:3

and 10:11. This reaction step can, conveniently be car- "tied out'in the presenceof water-soluble, non-volatile organic, or inorganieacids such, asp-toluene sulfonic acid, acetic acid, propionicacid, oxalic acid,sulfuric acid, phosphoric acid, or in the presence of water-soluble acid salts'such as ZnCla and NaHSOi. It is advantageous to exclude oxygen from the reaction and to operate under such conditions that the alcohol being formed during the reaction is continuously; distilled off from the reaction mixture, -A water-miscible solvent such'as dioxane, tetrahydrofurane, ethylene glycol dimethyl ether'fet'c maybe added to the reaction "mixture Qorder tdobtain a homogeneous mixture. Preferably, the C14 di-etheracetal is either heated with phosphoric acid in the presence of a water-miscible solvent to abo ut l00 C., the alcohol formed during the reaction being continuously removed fromtheTeaction mixture, "or boiled with acetic acid with additionof alkali acetate and some water, the alcohol formed during thereaetion being combined in the form of acetic-acid ester. On dilution of the reaction mixturewith water the crystalline C14 dialdehyde separates, which can be purified by recrystallisation, for example from ethyl alcohol or chloroform, or by sublima- Inorder to preventlosses of substance due to polymerisation and decomposition, it is recommended to avoid temperatures exceeding C: throughout the process and, in particular, to use the intermediates, i. e. the Cmdiacetal and C14 di-eth eracetal, in an undistilled form in the next step." 1,, t 1 The so 1 obtained' C14 dialdehyde [4:9-dimethyldodecatetraen (2 54:8210) yn (6) dial (1:12)] melts at165" C. and shows two absorption maxima in the ultra-violet spectrum atj37l'mp, E=53, 500, and at 391 m 'srqqdgt cone. ethanol), By partial hydro genation ofthe triple bond, which eanibe earriedout by reaction with one mole of hydrdgeriinthe presence of a palladium-lead catalyst, 4:9-dimethy1dodecapentaen- (2:4:6z8z10) dial (1:12) is formed. The cis form formed at first in the catalytic hydrogenation can be converted into the all-trans form by the action of light, heat or iodine.

This all-trans form of 4:9-dimethyldodecapentaen- (2:4:6:8:10)-dial-(l:l2) is also formed, as mentioned above, in the process according to the present invention, if 2:7 dimethyloctatrien (2:426) dial (1:8) of M. P. 161.5 to 162 C. is used as starting material which itself can be obtained from 2:7-dimethyloctadien-(2:6)- yn-(4)-dial-( 1:8) by the action of one mole of hydrogen in the presence of a palladium-lead catalyst and heating the hydrogenation product.

EXAMPLE C diacetal methyl octadien (2:6) yn (4) dial (1:8) in 120 parts' by'weight of ethyl ortho-formate a hot solution of 4 parts by weight of ammonium nitrate in 50 parts by volume of absolute alcohol is added and the mixture is allowed to stand for 48 hours, the mixture then gradually reaching room temperature. Then the reaction mixture is taken 'up in ether, washed with sodium bicarbonate solution and dried over potassium carbonate. After concentration of the ether solution the excess of ethyl ortho-formate as well as the formed ethyl formate are removed in vacuo from the condensation product. By distillation in a high vacuum there is obtained pure 2:7 dimethyloctadien (2:6) yn (4) tetraethyldialectal-(1:8) of B. P. 122 to 127 C. at 0.03 mm.; 11 1.4892; ultra-violet maxima: 273 m e=27,200, and 288 mu, s=22,600 (in conc. ethanol).

C14 di-etheracetal stirred for a further 3 hours at 35 C. and is then taken upin ether, washed with diluted sodium hydroxide solution and dried over potassium carbonate. After concentration of the ether solution 137 parts by weight of crude 4:9 dimethyldodecadien (4:8) yn (6) di-' ethoxy (3:10) tetraethyldiacetal (1:12) are obtained. The compound purified by distillation in a high vacuum boils .at 160-161 C. at 0.03 mm; n 1.4778; ultra-violet maxima: 274 I11p., e=26,200, and 290 mg, e=23,400 (in conc. ethanol).

C14 dialdehyde For hydrolysing the above diacetal the crude 4:9-dimethyldodecadien (4:8) yn (6) diethoxy (3:10)- tetraethyldiacetal-(l:12) is dissolved in a mixture of 800 parts by volume of dioxane, 200 parts by volume of Water and-35 parts by volume of 87% phosphoric acid, and traces" of hydroquinone are added thereto. The mixture is boiled for 7 hours under a nitrogen atmosphere, during which period a mixture of dioxane, alcohol and wateris slowly distilling otf through a column packed with Raschig rings. The reaction volume is maintained constant by dropwise addition of a mixture of dioxane and water. The hot reaction mixture is then poured with stirring onto about 2000 parts by volume of ice water, the 4:9 dimethyldodecatetraen (2:4:8z10) -yn- (6) dial (1:12) immediately precipitating in a crystalline form. The precipitate is sucked off and well 7 washed with water. After recrystallisation-from ethyl' alcohol and drying invacuo 45 parts by weight of the pure compound of B; P. 165 C. are obtained.

' What we claim is: V

RO\ put CH3 OR I Ho-o=oH-X on=c-on R0 on wherein X has the same meaning as above, and each R represents a lower alkyl radical; reacting the lattercompound with vinyl lower alkyl ether in the presence of an acidic condensation agent to produce a compound having the formula I wherein X has the same meaning as above, and each R represents a lower alkyl radical; and hydrolysing the latter compound in aqueous acidic medium to produce a compound having the formula 2. A process which comprises reacting a compound having the formula (EH; ([1113 oHGo=oH-X oH=ooHo wherein X represents a bivalent radical selected from the group consisting of CEC- and .--CH= CH- with a tri(lower alkyl) ester of a lower ortho-alkanoic acid in the presence of an acidic condensation agent to produce a compound having the formula R0 ([JH; ([3113 /OR o--o=ortX 'oH=c-oH no i on v wherein X has the same meaning 'as above and each R represents a lower alkyl radical.

3. A compound having the formula wherein X represents a bivalent radical selected from the 1 group consisting of CEC-- and CH=CH' and each R represents a lower alkyl radical.

4. A process which comprises reacting a compound having the formula R0 OR produce a compound having the formula wherein X represents a bivalent radical selected'from the group consisting of CEC- and CH=CH and each R represents a lower alkyl radical.

wherein X represents a bivalent radical selected from the group consisting of C= =.C and -CH=CH-, and each R represents a lower alkyl radical.

6. A process which comprises hydrolyzing a compound wherein X represents a bivalent radical selected from 15 the group consisting of -CEC and CH=CH, and each R represents a lower alkyl radical in aqueous acidic medium to produce a compound having the formula 6 9H: CH3 OHO-OH=CHG=CH--X-CH=OGH=CHOHO wherein X represents a bivalent radical selected from the group consisting of -CEO and CH=CH--.

7. A compound having the formula OH: OH:

OHOOH=CHO=OH-XOH=OGH=CHOHO wherein X represents a bivalent radical selected from the group consisting of --CEC- and CH=CH-.

8. 4:9 dimethyl dodecatetraen (2:4:8:10) yn- (6)-dia1-(1:12).

9; 4:9 dimethyl dodecapentaen (2:4:6z8: 10) dial- (1:12).

No references cited. 

1. A PROCESS WHICH COMPRISES REACTING A COMPOUND HAVING THE FORMULA 